The long-term objective of this line of research is to identify brief, behavioral interventions that enhance treatment adherence in Obstructive Sleep Apnea (OSA). Specifically, we will build upon our empirical data from the first award to test the efficacy of enhanced behavioral therapies to improve treatment adherence. We have identified critical periods when adherence patterns develop in OSA treatment and have noted the effects of behavioral interventions on adherence. These methods provide a potential mechanism for enhancing adherence, subsequently improving the quality of life and functional capabilities of patients with this prevalent sleep disorder. The aims of the application are: 1) to examine the efficacy of enhanced motivational enhancement therapy (MET+) and educational therapy (ED+) for improving adherence to treatment in OSA;2) to examine the degree to which changes in self-efficacy mediate the effects of these therapies;and 3) to examine the relationship between amount of treatment and changes in clinical outcome variables. We will randomize 300 participants with [symptomatic mild] to severe OSA into one of three groups for this study: 1) MET+, with 2 face-to-face sessions in the beginning of treatment, strategically timed motivational phone calls providing adherence feedback using Motivational Interviewing, and follow-up phone calls at 1 and 3 months;2) ED+, with the same contact time as MET+ but providing didactic educational counseling and problem solving;and 3) standard care. Our behavioral interventions both improved adherence in our initial study, although moderators of efficacy were identified and the effects were not maintained. We will now employ the use of electronic monitoring of adherence data, accessed daily, to identify when participants begin to adhere poorly [(defined within the protocol)]. We will time our phone sessions to coincide with these difficulties, when participants may be more receptive to assistance and vulnerable to relapse. We believe that enhancing these therapies with individualized attention early in treatment and continued follow-up over 3 months will augment their effects and provide the optimal conditions under which to test their different contents. The strength of this application lies in our tested interventions and the method of measuring and using adherence data in the therapy. This will be the first study to employ psychological theories of behavior change to enhance treatment adherence in OSA with this new technology.